Genetic and behavioural divergence among desert spring amphipod populations

1. Random amplification of polymorphic DNA (RAPD) analyses and behavioural trials were conducted on eleven Hyalella azteca populations and one population of H. montezuma from lakes and springs across northern Arizona, U.S.A. Genetic distances among populations were calculated based on fifty-five RAPD markers. 2. A cluster analysis indicated two genetic lineages among the Hyalella populations. One group consisted of populations inhabiting lakes with submerged vegetation, while a second group consisted of populations that clung to roots of emergent vegetation. Behaviour also diverged between these two groups in laboratory trials: amphipods from the submerged vegetation lineage spent significantly more time swimming than did those from the emergent vegetation lineage. 3. Based on patterns in genetic distance data, it is suggested that a xeric landscape may promote diversity among passively dispersed invertebrates.